History of Autism • Initially, autism blamed on parents being “cold, distant, or rejecting” of their children – “Refrigerator Mothers” • Research has shown that parenting cannot be the cause of autism – e.g., similar parenting for siblings with autism as without • Any differences noted in parenting is now seen as a reaction to child’s emotional distance and non-social behaviors • Large increase in number of cases since it was first identified in the 1930’s and 1940’s by Leo Kanner and Hans Asperger • Theories surged looking for environmental factors to explain this “epidemic,” with a large focus on vaccines but no data to support them
Correlation vs. Causation • History of autism highlights the importance of not jumping to conclusions • CORRELATION DOES NOT EQUAL CAUSATION! • E.g., higher rates of autism in children born in urban areas • Research has shown no connection between vaccines and autism, but some of the public still holds fear of vaccinations
Epidemic of Autism? • Increase in prevalence doesn’t necessarily mean an epidemic • Increasing diagnostic rates most likely due to broadened diagnostic criteria and increased awareness/services, rather than increased rates of the disorder actually occurring (diagnosed or not) • Catching all of the cases that previously may have been missed (e.g., high functioning individuals) or categorized into other labels (e.g., intellectual disability; learning disorders) • Possible that there are more cases than in the past – continued, careful epidemiological research will help tease this apart
Causes of ASD • Combination of genes and environment, with multiple genes involved • “The Autisms” – ASD really made up of many different disorders, explaining the heterogeneity, but we can’t differentiate them yet • E.g., Gene for Rett’s Disorder identified, form of autism only in girls with particular repetitive hand and feet movements • Genetic factors: • Higher prevalence (~20%) in siblings of children with ASD • Increased odds if you have more than one sibling with ASD • Higher concordance among MZ twins vs. DZ twins
Abrahams and Geschwind 2009
Causes of ASD, cont. • Other Biological Factors – assessed primarily through neuroimagining studies and other brain-based research methods (e.g., EEG/ERP) • Rapid brain growth in early development • Research into structure and function of brain areas related to emotions, sensorimotor movement, and higher level thinking • Possible abnormalities with mirror neurons and/or neurotransmitters: • Mirror neurons – fire when individual performs an action or another individual, connected with imitation and learning and may relate to social and emotional processes • Oxytocin – related to mother-infant attachment and other social behaviors
Causes of ASD, cont.
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